EP2610921A1

EP2610921A1 - Solar cell and solar cell module including same

Info

Publication number: EP2610921A1
Application number: EP11822022.7A
Authority: EP
Inventors: Do Won Bae
Original assignee: LG Innotek Co Ltd
Current assignee: LG Innotek Co Ltd
Priority date: 2010-09-01
Filing date: 2011-04-27
Publication date: 2013-07-03
Anticipated expiration: 2031-04-27
Also published as: EP2610921A4; WO2012030047A1; JP2013536997A; KR20120022229A; CN103053030B; KR101154718B1; CN103053030A; EP2610921B1; JP5775586B2

Abstract

Disclosed are a solar cell and a solar cell module including the same. The solar cell includes a support substrate having first and second surfaces opposite to each other, a photoelectric conversion part disposed on the first surface and including a first electrode, a light absorbing layer, and a second electrode, and a collecting electrode electrically connected to at least one of the first and second electrodes and disposed on the second surface.

Description

Technical Field

The embodiment relates to a solar cell and a solar cell module including the same.

Background Art

Recently, as energy consumption is increased, a solar cell has been developed to convert solar energy into electrical energy. The solar cell has an important issue to improve the photoelectric conversion efficiency.

Disclosure

Technical Problem

The embodiment provides a solar cell capable of increasing an effective region which can generate electrical energy by absorbing the solar light, and a solar cell module including the same.

Technical Solution

According to the embodiment, there is provided a solar cell including a support substrate having first and second surfaces opposite to each other, a photoelectric conversion part disposed on the first surface and including a first electrode, a light absorbing layer, and a second electrode, and a collecting electrode electrically connected to at least one of the first and second electrodes and disposed on the second surface.
Meanwhile, a solar cell module according to the embodiment includes the solar cell and a junction box disposed on the second surface of the support substrate.

Advantageous Effects

As described above, according to the solar cell of the embodiment, since the collecting electrode is positioned on the bottom surface of the support substrate, the area of the photoelectric conversion part positioned on the top surface of the support substrate can be maximized. Accordingly, the effective area of the solar cell can be increased. In addition, since the extension part and the collecting electrode are positioned on the bottom surface of the support substrate, which does not receive the solar light, the extension part and the collecting electrode can be formed with the wide area. Accordingly, the contact resistance can be reduced so that the efficiency of the solar cell can be improved.
In addition, since the extension part extends to the bottom surface of the support substrate while surrounding the lateral side of the support substrate. Accordingly, the collect electrode can be positioned on the bottom surface of the support substrate in the simple structure.
In addition, since the junction box is positioned on the bottom surface of the support substrate, the collecting electrode can be aligned in line with the junction box. Accordingly, the connection structure between the collecting electrode and the junction box can be simplified.

Description of Drawings

FIG. 1 is a plan view showing a solar cell module according to the embodiment;
FIG. 2 is a sectional view taken along line I-II of FIG. 1;
FIG. 3 is a bottom view showing the solar cell module according to the embodiment;
FIG. 4 is a bottom view showing a solar cell module according to a modification;
FIGS. 5 to 8 are sectional views showing the manufacturing process of a solar cell according to a first embodiment; and
FIGS. 9 to 11 are sectional views showing the manufacturing process of a solar cell according to a second embodiment.

Best Mode for Invention

In the description of the embodiments, it will be understood that, when a layer (or film), a region, a pattern, or a structure is referred to as being "on" or "under" another substrate, another layer (or film), another region, another pad, or another pattern, it can be "directly" or "indirectly" on the other substrate, layer (or film), region, pad, or pattern, or one or more intervening layers may also be present. The thickness and size of each layer (or film), each region, each pattern, or each structure shown in the drawings may be exaggerated, omitted or schematically drawn for the purpose of convenience or clarity. In addition, the size of elements does not utterly reflect an actual size.
Hereinafter, the embodiment will be described in detail with reference to accompanying drawings.
FIG. 1 is a plan view showing a solar cell module according to the embodiment, FIG. 2 is a sectional view taken along line I-II of FIG. 1, and FIG. 3 is a bottom view showing the solar cell module according to the embodiment.
Referring to FIGS. 1 to 3, a solar cell module 100 according to the embodiment includes a solar cell 110 and a junction box 120 of stably collecting electricity generated from the solar cell 110 to prevent the reversal current of the electricity.
In this case, referring to FIG. 2, the solar cell 110 includes a support substrate 10, a photoelectric conversion part 20 formed on the support substrate 10, and a collecting electrode 30 to collect electricity generated from the photoelectric conversion part 20. According to the present embodiment, a plurality of photoelectric conversion parts 20 are provided, and adjacent photoelectric conversion parts 20 are connected to each other in series, thereby defining a plurality of cells. Hereinafter, the details thereof will be made in detail below.
The support substrate 10 has a plate shape, and supports the photoelectric conversion part 20 and the collecting electrode 30 formed thereon. The support substrate 10 may include an insulator including glass or plastic. For example, the support substrate 10 may include soda lime glass. However, the embodiment is not limited thereto, and the support substrate 10 may include a metallic substrate. In other words, the support substrate 10 may include a rigid material or a flexible material according to the characteristics of the solar cell module 100.
Each photoelectric conversion part 20 formed on a first surface 12 (the top in drawings; hereinafter, referred to as "top surface") includes a first electrode 21, a light absorbing layer 23, and a second electrode (window layer) 29. Hereinafter, the connection structure of adjacent photoelectric conversion parts 20 will be described after describing the photoelectric conversion parts 20 while focusing on one photoelectric conversion part 30.
The first electrode 21 may include a material representing superior electrical characteristics. For example, the first electrode 21 may include molybdenum (Mo), copper (Cu), nickel (Ni), aluminum (Al), or the alloy thereof.
A light absorbing layer 23 is formed on the first electrode 21 to convert the solar light into the electrical energy. According to the present embodiment, the light absorbing layer 23 may include a non-silicon semiconductor material.
The light absorbing layer 23 may include a group I-III-IV compound. For example, the light absorbing layer 23 may include a Cu-In-Ga-Se (Cu (In, Ga) Se2; CIGS)-based crystal structure, a Cu-In-Se-based crystal structure, or a Cu-Ga-Se-based crystal structure.
In addition, the light absorbing layer 23 may include a group II-IV compound or a group III-IV compound. For example, the light absorbing layer 23 may include cadmium (Cd) -tellurium (Te) compound, or gallium (Ga)-arsenic (As) compound.
A buffer layer 25 and a high resistance buffer layer 27 may be formed on the light absorbing layer 23.
The buffer layer 25 is formed on the light absorbing layer 23 to reduce the difference in the lattice constant and the energy bandgap from the second electrode 29. For example, the buffer layer 25 may include CdS.
The high resistance buffer layer 27 prevents the buffer layer 25 from being damaged when forming the second electrode 29. For example, the high resistance buffer layer 27 may include zinc oxide (ZnO).
The second electrode 29 may include a transparent conductive material which is transparent to allow light to be incident into the second electrode 29 and provides the function of an electrode due to the conductivity thereof. In addition, the second electrode 29 has the characteristic of an N type semiconductor to form an N type semiconductor layer together with the buffer layer 25, thereby forming a PN junction structure together with the light absorbing layer 23 serving as a P type semiconductor layer. To this end, for example, the second electrode 29 may include Al doped zinc oxide (AZO).
According to the present embodiment, since the light absorbing layer 23 including a CIGS-based compound, a CIS-based compound, a CGS-based compound, a Cd-Te compound, or a Ga-As compound is provided, the light absorbing layer 23 can represent superior photoelectric conversion efficiency.Accordingly, the solar cell module 100 is formed with a thin thickness, so that the material can be saved, and the use range of the solar cell module 100 can be expanded. In addition, the degradation of the light absorbing layer 23 caused by the light is reduced, so that the life span of the solar cell module 100 can be increased.
However, the present embodiment is not limited thereto. Accordingly, the solar cell module 100 may include a photoelectric conversion part constituting a dye-sensitized solar cell, an organic solar cell, and a silicon solar cell.
Each photoelectric conversion part 20 corresponds to a cell C of each solar cell 110, and the adjacent photoelectric conversion parts 20 are connected to each other in series. In more detail, the first electrodes 21 may be spaced apart from each other while representing a pattern corresponding to the cell C of each solar cell 110. In addition, the light absorbing layer 23, the buffer layer 25, the high resistance buffer layer 27, and the second electrode 29 may be divided by a division pattern 44 corresponding to a cell of each solar cell 10. The first electrode 21 corresponding to a specific cell C may be connected to the second electrode 29 corresponding to a cell C adjacent to the specific cell C through a contact pattern 42 formed in the light absorbing layer 23, the buffer layer 25, and the high resistance buffer layer 27.
Therefore, each photoelectric conversion part 20 corresponding to the cell C of each solar cell 110 may be defined as the region in which the first electrode 21, the light absorbing layer 23, the buffer layer 25, the high resistance buffer layer 27, and the second electrode 29 are sequentially laminated on each other.
The collecting electrode 30 is electrically connected to at least one of the first and second electrodes 21 and 29 of the photoelectric conversion parts 20 to collect current. According to the present embodiment, the collecting electrode 30 includes first and second collecting electrodes 31 and 32, and the first and second collecting electrodes 31 and 32 are positioned at the extension parts 214a and 214b of the first electrode 21.
In more detail, the first electrode 21 includes an electrode part 212 constituting the photoelectric conversion part 20 while being placed on the top surface 12 of the support substrate 10 and the extension parts 214a and 214b extending from the top surface 12 of the support substrate 10 to a second surface 14 (the bottom of the drawings; hereinafter, referred to as "bottom surface"). The extension parts 214a and 214b include the first extension part 214a extending from the electrode part 212 placed at one side (the left side of the drawings; hereinafter, referred to as a left side) of the support substrate 10 toward the bottom surface 14 of the support substrate 10, and the second extension part 214b extending from the electrode part 212 placed at an opposite side (the right side of the drawings; hereinafter, referred to as a right side) of the support substrate 10 toward the bottom surface 14 of the support substrate 10. The first and second extension parts 214a and 214b are spaced apart from each other on the bottom surface 14 of the support substrate 10.
In this case, the first extension part 214a extends from the electrode part 212 (the most left side electrode part in the drawings) of the first electrode 21 without the contact pattern 42, and the second extension part 214b extends from the electrode part 212 (the most right side electrode part in the drawings) of the first electrode 21 directly connected to the second electrode 29 through the contact pattern 42. Accordingly, both of the first and second collecting electrodes 31 and 32 can be placed on the same first electrode 21, and the photoelectric conversion parts 20 can be connected to each other in series.
The first collecting electrode 31 may make contact with the first extension part 214a on the bottom surface 14 of the support substrate 10, and the second collecting electrode 32 may make contact with the second extension part 214b on the bottom surface 14 of the support substrate 10.
As described above, according to the present embodiment, since the first and second collecting electrodes 31 and 32 are placed on the bottom surface 14 of the support substrate 10, the area of the photoelectric conversion part 20 provided on the top surface 12 of the support substrate 10 can be maximized. In addition, according to the related art, since the first and second collecting electrodes 31 and 32 are formed on the top surface 12 of the support substrate 10 together with the photoelectric conversion part 20, the area of the photoelectric conversion part 20 must be reduced by the area of the first and second collecting electrodes 31 and 32. Accordingly, the effective area of the solar cell 110 is reduced. However, according to the present embodiment, since the first and second collecting electrodes 31 and 32 are formed on a surface different from that of the photoelectric conversion part 20, the area, in which the photoelectric conversion part 20 is formed, is maximized, so that the effective area of the solar cell 110 can be increased.
Inaddition, since the first and second extension parts 214a and 214b and the first and second collecting electrodes 31 and 32 are provided on the bottom surface 14 of the support substrate 10 that does not receive the solar light, the first and second extension parts 214a and 214b and the first and second collecting electrodes 31 and 32 may be formed with a wide area. Therefore, the efficiency of the solar cell 110 can be improved by reducing contact resistance.
In this case, the first and second extension parts 214a and 214b may be spaced apart from each other by the distance of about 60µm or more on the bottom surface 14 of the support substrate 10. Inotherwords, since the first and second extension parts 214a and214b are spaced apart from each other to the extent that the first extension part 214a is not electrically connected to the second extension part 214b, the areas of the first and second extension parts 214a and 214b and the first and second collecting electrodes 31 and 32 can be maximized.
Although FIG. 3 shows that the extension parts 214a and 214b and the first and second collecting electrodes 31 and 32 have a rectangular plane shape, the present embodiment is not limited thereto. Accordingly, as shown in FIG. 4, extension parts 216a and 216b may include protrusion parts P1 and P2, the protrusion P1 of the first extension part 216a and the protrusion part P2 of the second extension part 216b may be alternately provided, and the first and second collecting electrodes 131 and 132 may have shapes corresponding to the first and second extension parts 216a and 216b.
As described above, the first and second extension parts and the first and second collecting electrodes may be variously modified, and the modifications are within the technical scope of the present embodiment. For reference, a protective film (reference numeral 50 of FIG. 2) and the junction box (reference numeral 120 of FIG. 3) are not shown in FIG. 4 for the brief description.
Referring to FIGS. 1 and 2 again, the first and second extension parts 214a and 214b surround the lateral side of the support substrate 10 while extending to the bottom surface 14 of the support substrate 10. Accordingly, the first and second collecting electrodes 31 and 32 can be positioned on the bottom surface 14 of the support substrate 10 in the simple structure. In other words, the first and second collecting electrodes 31 and 32 can be positioned on the bottom surface 14 of the support substrate 10 through the simple manufacturing process without the process of forming additionally through holes in the support substrate 10.
For example, although the collecting electrode 30 is formed on the first electrode 21 adj acent to the support substrate 10 according to the present embodiment, the present embodiment is not limited thereto. Therefore, the collecting electrode 30 may be formed on the second electrode 29, or may be formed on each of the first and second electrodes 21 and 29.
In addition, a protective film 50 surrounds the solar cell 110 to protect the solar cell 110, and an insulating sealing member 60 is formed at the lateral side of the solar cell 110 to make the solar cell 110 in the form of a module. In addition, the material constituting the solar cell 110 can be firmly fixed by using the frame 70 surrounding the solar cell 110.
In addition, referring to FIG. 3, the junction box 120 may be positioned on the protective film 50 formed on the bottom surface 14 of the support substrate 10 having the first and second collecting electrodes 31 and 32. The first junction box 120 may receive a circuit board having diodes mounted thereon, and may be connected to the first and second collecting electrodes 31 and 32 through a cable 122. According to the present embodiment, since the first and second collecting electrodes 31 and 32 are aligned in line with the junction box 120, an additional hole used to connect the first and second collecting electrodes 31 and 32 to the junction box 120 may not be formed in the support substrate 10. As described above, since the connection structure of the first and second collecting electrodes 31 and 32 and the junction box 120 can be simplified, the size of the solar cell module 100 can be reduced, and the manufacturing process of the solar cell module 100 can be simplified.
However, the embodiment is not limited thereto, and the junction box 120 and the cable 122 may not be formed.
Hereinafter, the method of manufacturing the solar cell according to the first embodiment will be described in more detail with reference to FIGS. 5 to 8. FIGS. 5 to 8 are sectional views showing the manufacturing process of the solar cell according to the first embodiment.
First, as shown in FIG. 5, a tape 16 is formed on the bottom surface 14 of the support substrate 10. The tape 16 may be formed in a region without the first extension part (reference numeral 214a of FIG. 2) and the second extension part (reference numeral 214b of FIG. 2).
The tape 16 may include a mask material such as metal, ceramic, or polymer.
Thereafter, as shown in FIG. 6, a conductive material layer 220 including a conductive material is formed on the whole surface of the support substrate 10. When performing the process of forming the conductive material layer 220, the conductive material is formed on all of the front surface, the rear surface, and the lateral side of the support substrate 10 by tilting a source to supply the conductive material and/or the support substrate 10. The deposition scheme may include various processes such as an electrochemical vapor deposition (EVD) process, or a spray process.
Thereafter, as shown in FIG. 7, the tape (reference numeral 16 of FIG. 5c) is removed. In this case, the conductive material layer 220 formed on the tape 16 is removed, thereby forming the first electrode layer 222 including the electrode part and the first and second extension part.
Subsequently, as shown in FIG. 8, the first electrode 21 including the electrode part 212 having a pattern corresponding to each cell is formed by patterning the first electrode layer 222.
Then, after forming the light absorbing layer (reference numeral 23 of Fig. 2), the buffer layer (reference numeral 25 of FIG. 2), and the high resistance buffer layer (reference number 27 of FIG. 2), the contact pattern (reference numeral 42 of FIG. 2) may be formed, the second electrode (reference numeral 29 of FIG. 2) may be formed, and the division pattern (reference numeral 44 of FIG. 2) may be formed. Accordingly, the solar cell 110 of FIG. 2 may be formed. Since the above process may be variously performed, the detail thereof will be omitted.
According to the present embodiment, the first electrode 21 having the first and second extension parts 214a and 214b may be formed on the bottom surface 14 of the support substrate 10 through the simple process.
Although the tape 16 is used according to the embodiment described above, various schemes such as a scheme of using a mask may be employed.
Hereinafter, a method of fabricating a solar cell according to a second embodiment will be described with reference to FIGS. 9 to 11. FIGS. 9 to 11 are sectional views showing the manufacturing process in a method of fabricating the solar cell according to the second embodiment. Hereinafter, the details of a process identical to or similar to a process of the first embodiment will be omitted, and the process different from the process of the first embodiment will be described.
First, as shown in FIG. 9, a conductive material layer 220 is formed on the whole surface of the support substrate 10 by dipping the support substrate 10 into a plating solution.
Therefore, as shown in FIG. 10, the first electrode layer 232 may be formed by removing the conductive material layer (reference numeral 230 of FIG. 5a) of the first extension part (reference numeral 214a of FIG. 2) and the second extension part (reference numeral 214b of FIG. 2). In order to remove the conductive material layer 230 between the first and second extension parts 214a and 214b, a mechanical scheme of performing a scribing process using a tip, a laser scheme, an etching scheme, or a sand blast scheme may be used.
Thereafter, as shown in FIG. 11, the first electrode 21 including the electrode part 212 having a pattern corresponding to each solar cell is formed by patterning the first electrode layer 232.
Thereafter, after forming the light absorbing layer (reference numeral 23 of FIG. 2), the buffer layer (reference numeral 25 of FIG. 2), and the high reference buffer layer (reference numeral 27 of FIG. 2), the contact pattern (reference numeral 42 of FIG. 2) is formed, and the second electrode (reference numeral 29 of FIG. 2) is formed. Thereafter, the division pattern (reference numeral 44 of FIG. 2) may be formed. Therefore, the solar cell 110 of FIG. 2 may be formed. Since the above process can be variously performed, the detail thereof will be omitted.
Any reference in this specification to "one embodiment," "an embodiment," "example embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

A solar cell comprising:
a support substrate having first and second surfaces opposite to each other;

a photoelectric conversion part disposed on the first surface and including a first electrode, a light absorbing layer, and a second electrode; and

a collecting electrode electrically connected to at least one of the first and second electrodes and disposed on the second surface.
The solar cell of claim 1, wherein at least one of the first and second electrodes includes an electrode part disposed on the first surface and an extension part extending from the first surface to the second surface, and the collecting electrode makes contact with the extension part.
The solar cell of claim 2, wherein the extension part extends from the first surface to the second surface while surrounding a lateral side of the support substrate.
The solar cell of claim 1, wherein the first electrode, the light absorbing layer, and the second electrode are sequentially laminated on the first surface of the support substrate, and the first electrode comprises an electrode layer positioned on the first surface and an extension part extending from the first surface to the second surface.
The solar cell of claim 4, wherein first and second extension parts have a width of about 60µm or more.
The solar cell of claim 4, wherein the extension part comprises a first extension part extending from one side of the electrode part and a second extension part extending from an opposite side of the electrode part and spaced apart from the first extension part on the second surface, and
wherein the collecting electrode comprises a first collecting electrode making contact with the first extension part and a second collecting electrode making contact with the second extension part.
The solar cell of claim 6, wherein the photoelectric conversion part includes a plurality of photoelectric conversion parts connected to each other in series, so that the electrode part of the first electrode, the light absorbing layer, and the second electrode comprises a plurality of electrode parts, a plurality of light absorbing layers, and a plurality of second electrodes, respectively, and
wherein the first extension part extends from the electrode part of the first electrode that is not connected to the second electrode through a contact pattern, and the second extension part extends from the electrode part of the first electrode that is connected to the second electrode through the contact pattern.
A solar cell module comprising:
a solar cell comprising a support substrate having first and second surfaces opposite to each other; a photoelectric conversion part disposed on the first surface and including a first electrode, a light absorbing layer, and a second electrode; and a collecting electrode electrically connected to at least one of the first and second electrodes and disposed on the second surface; and

a junction box on the second surface of the support substrate.
The solar cell module of claim 8, wherein at least one of the first and second electrodes includes an electrode part on the first surface and an extension part extending from the first surface to the second surface, and the collecting electrode makes contact with the extension part.
The solar cell module of claim 9, wherein the extension part extends from the first surface to the second surface while surrounding a lateral side of the support substrate.